Hellenism is Paganism ancient Greek religion and culture, focus on the worship of the Olympian gods and goddesses, such as Zeus, Athena, Apollo, Artemis, and others.
Hellenism is a specific tradition within the broader category of paganism, characterized by its focus on ancient Greek religion and culture.
Paganism includes, but is not limited to, Hellenism.
Same with Hermeticism that have it's roots on Egypt and Greece: 
Now Wicca is actually what people call Neo-Paganism as it was crafted by Gerald Brousseau Gardner on 1950 and have it's roots on Freemasonry, Rosicrucian and Aleister Crowley Satanism (which are not Pagan). 
that's exactly what im saying, if you generalize all paganism to the greek culture you WILL fill your bubble with ppl that claim to be pagan and are completely disrupt from your paganism, even if they are or not pagan
